We propose to investigate the cellular basis of T cell suppression of the immune response to allogeneic and tumor antigens by adjuvant. Proposed research in the alogeneic model will focus on: 1) the effect of adjuvant on the generation of suppressor cells in the thymus and peripheral lymphoid tissue; 2) in vivo manipulation of an immune response by adoptive transfer of adjuvant activated T lymphocyte subpopulations; and 3) an assesment of the interaction of adjuvant-activated T cells and macrophages. Subsequently we will apply the information gained in the allogeneic system to the syngeneic Murine Sarcoma Virus system to determine the effect of adjuvant on the response of T, B and null cells to syngeneic tumor antigens.